Definition: In this task, you are given an input list A comprising of numbers and alphabets. You need to extract and sort the unique alphabets in the list. The alphabets in the input list will only be in lowercase. Return -1 if there is no alphabet in the input list.
Input: ['k', '2125', '9249', '3721', '597', '3997', '7605', 'd', 'i']

d, i, k